Action of diazomethane on phenol liberates

Answer:  N₂

Diazomethane (CH₂N₂) is a powerful methylating agent. When it reacts with phenol, the phenolic –OH group gets methylated to form anisole (methoxybenzene). During this reaction, nitrogen gas (N₂) is liberated as a by-product:

C₆H₅OH + CH₂N₂ → C₆H₅OCH₃ + N₂

Why is this important for NEET & JEE?

This reaction is a standard example of organic chemistry for entrance exams like NEET and JEE. Students should remember that diazomethane methylates phenols and alcohols while liberating N₂ gas.